Psychiatric syndromes like hypochondriasis, somatization disorder and Munchausen’s disorder could be uncharitably characterized by the layman as ‘he’s making it up, innit’.  Not as simple as that alas, which one of the reason you have to train psychiatrists rather than pull them off the street.

Munchausen syndrome (also known as factitious disorder): the patient seeks medical attention by the intentional production or feigning of symptoms.  The motivation for this is considered not to be known to the patient and he/she keeps their stimulation or induction secret.  It was named (1) after Rudolf Raspe’s 1785 fictional German cavalry officer, Baron Karl von Munchausen, who always lied fantastically about his military exploits.  A classic case might have what is called a ‘grid iron’ stomach because of all the scars from numerous abdominal operations.  Also a feature is ‘perigrination’ where a patient will move from hospital to hospital seeking treatment, once rejected from a department.

Munchausen syndrome by proxy: This was first defined by Meadows (2) and has become controversial.  Defined as ‘the deliberate production or feigning of physical or psychological symptoms or signs in another person who is under that individual’s care’.  it is considered to be a form of child abuse.  It is also not unknown for healthcare workers to fabricate health crises in their patients so that they can ’save’ them. 

Hypochondriasis: the patient is convinced that they have a life-threatening illness, despite evidence to the contrary.  They often misattribute normal bodily sensations as being pathological. 

Malingering: the patient knowingly fabricates a medical illness for known gain.  This is considered to be rare. 

Somatization disorder: With this a patient presents with multiple, medically unexplained symptoms. Originally described as Briquet’s syndrome in the 1960s.  Patients sometimes show a lack of concern for the nature and implications of their symptoms and the presentation may also be illogical for example, the patient may complain of intolerable pain, but still appear calm and composed.

So, in summary, if they’re doing it, but they don’t know why then it’s Munchausen’s syndrome; if they’re doing it to someone else and they don’t know why then that’s Munchausen’s by proxy; if they think they’re going to die and you can’t persuade them otherwise then that’s hypochondriasis; if they’re not doing it, but they feel unwell but are pretty vague about it then they’re somatizing and if they’re doing it, they know why and they want money for it then they’re malingering.  Clear?

Addendum: Jan-Michael has asked about how the above relate to conversion disorders, which is a good question.  Conversion disorders are presumed to be psychogenic in origin.  The patient experiences a conflict or trauma of some kind and the unpleasant affect is transformed (/converted) into symptoms.  Examples are dissociative amnesia, dissociative fugue, dissociative stupor, trance and possession disorders, dissociative disorders of movement and sensation and dissociative convulsions. 

In common with somatisation disorder, both involve physical symptoms and with both there is no evidence of a physical disorder that might explain these symptoms.  The difference is that to diagnose dissociative disorder there should be clear evidence of psychological causation for the symptoms, even if the patient denies it.  There is no need for this to make a somatisation disorder diagnosis.  Also with somatization disorder, the patient tends to present with a variety of vague symptoms whilst in a dissociate disorder the symptoms are more focused. 

In terms of classification, disorders with a predominantly physical or somatic mode of presentation are grouped together.  In ICD-10 F40-48 covers neurotic, stress related and somatoform disorders.  Within this F44 covers Dissociative [conversion] disorders and F45 covers somatoform disorders.  Somatoform disorder is classified within this as F45.0 and hypochondrical disorder is classified as F45.2.  Malingering is classified elsewhere as Z76.5 (Z0-Z99 Factors influencing health status and contact with health services) and Munchausen’s F68.1 ‘intentional production or feigning of symptoms or disabilities either physical or psychological [factitious disorder]‘ (F68 other disorders of adult personality and behaviour)

(1) Asher, R. (1951). Munchausen’s syndrome. Lancet, i, 339–41.

(2) Meadow, R. (1977). Munchausen syndrome by proxy: the hinterland of child abuse. Lancet, ii, 343–5.